In situ angle-resolved photoemission study on La_{1 - X}Sr _xMnO₃ thin films grown by laser MBE

We have performed an in situ angle-resolved photoemission study of atomically flat surfaces of La_{1 - x}Sr_xMnO₃ (LSMO) single-crystal thin films grown on SrTiO₃ (0 0 1) substrates by laser molecular beam epitaxy, and investigated the changes in the band structure induced by hole-doping. The band structures of LSMO x = 0.4 thin films consist of several highly dispersive O 2p-derived bands at the binding energies of 2.5-7 eV, almost dispersionless Mn 3d t_2g bands at ∼2 eV, and a dispersive Mn 3d e_g-derived majority band at ∼0.5 eV. We find that the energy positions of these bands monotonically shift toward higher binding energy with decreasing hole concentration in a rigid-band manner, whereas the lower binding energy part of the e_g-derived emission within 1.5 eV of the Fermi level (E_F) gradually disappears. These results suggest that the simple rigid-band model does not describe the electronic structure near E_F of LSMO.